1. Field of the Invention
This invention relates to wire feeders of a planetary type. In one of its aspects, the invention relates to a planetary wire feeder with a plurality of sets of driven rollers and means to adjust the spacing between the rollers and the pressure applied by the rollers.
2. State of the Prior Art
Planetary wire feeders are well known and are used advantageously for feeding wire such as welding wire in a welding operation. It is necessary in such operations to feed the wire consistently and at a predetermined rate so that the welder can concentrate on the quality of weld and need not worry about the sufficiency of the wire at the weld. If the rate of wire feed is too small, the weld bead is too small and the weld consequently may not be strong enough. If the wire feeding is too fast, then the weld bead is too large and excess welding wire is used. If the feeding is erratic, the weld may have weak portions.
Examples of planetary wire feeders are disclosed in the Karnes et al U.S. Pat. Nos. 3,738,555 (issued June 12, 1973) and 3,744,694 (issued July 10, 1973) and in Samokovliski et al U.S. Pat. Nos. 4,049,172 (issued Sept. 20, 1977) and 4,085,880 (issued Apr. 25, 1978). In the Karnes et al U.S. Pat. No. 3,744,694 a wire feeding chuck having two sets of tandem drive rollers is disclosed.
These wire feeding chucks are relatively complex in construction and the commercial embodiments are not completely satisfactory in consistently feeding welding wire in a welding operation. Further, the structures do not readily allow for adaptability to feeding radically different size wires.